Thousands of Iranians chanted “Death to America” near the old U.S. embassy on Monday, the 40th anniversary on the seizure of the mission, with the country’s army chief comparing the United States with a poisonous scorpion intent on harming Iran.

State television showed crowds packing the streets around the former mission, dubbed the “den of spies” after Iran’s 1979 Islamic revolution. Marches and rallies were being held in some 1,000 communities across the country, state media said.

Hardline Islamist students stormed the embassy soon after the fall of the U.S.-backed shah, and 52 Americans were held hostage there for 444 days. The two countries have been enemies ever since.

“Our fight with America is over our independence, over not submitting to bullying, over values, beliefs and our religion,” army chief Major General Abdolrahim Mousavi said in a speech at the rally outside the former embassy.

“They (Americans) will continue their hostilities, like the proverbial poisonous scorpion whose nature it is to sting and cannot be stopped unless it is crushed,” Mousavi said in remarks carried by state TV.

Meanwhile, Iran’s parliament gave initial approval to a measure requiring schoolbooks to inform students about “America’s crimes.” Lawmakers also chanted “Death to America.”

Relations between the two countries have reached a crisis over the past year since U.S. President Donald Trump abandoned a 2015 pact between Iran and world powers under which it accepted curbs to its nuclear program in return for lifting sanctions.

The United States has reimposed sanctions aimed at halting all Iranian oil exports, saying it seeks to force it to negotiate to reach a wider deal.

Khamenei has banned Iranian officials from holding talks unless the United States returns to the nuclear deal and lifts all sanctions.